The US has added a third option to its arsenal of COVID-19 vaccines after the FDA authorised Johnson & Johnson's single-dose candidate Ad26.COV2.S for emergency use in people 18 years and older on Saturday. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, stated that "after a thorough analysis of the data," the vaccine was found to meet the agency's expectations for safety and effectiveness. "With today's authorisation, we are adding another vaccine in our medical toolbox to fight this virus," he added.
The decision comes on the heels of a unanimous FDA advisory panel endorsement the day before, as well as an assessment by agency scientists that said the vaccine appeared safe in clinical trials and protected against SARS-CoV-2 infection, with "high" efficacy against severe/critical illness across variants.
Johnson & Johnson stated that it is shipping its vaccine "immediately," with a potential rollout of 3 million to 4 million doses this coming week, according to recent comments by White House COVID-19 response coordinator Jeff Zients. The company said it will deliver more than 20 million doses to the US in March, and honour its contract to supply the country with 100 million doses in the first half of 2021. It added that it plans to file for a biologics license application with the FDA later this year.
“We believe [our] single-shot COVID-19 vaccine is a critical tool for fighting this global pandemic, particularly as it shows protection across countries with different variants," remarked Johnson & Johnson chief scientific officer Paul Stoffels. He also highlighted the vaccine's benefit "against the most dire outcomes of hospitalisation and death," saying it "will help ease the burden on people and the strain on health systems worldwide."
Emergency-use authorisation (EUA) for the Ad26 vector-based candidate follows authorisations granted first to Pfizer and BioNTech's BNT162b2 and then Moderna's mRNA-1273 back in December. Both of those work by using mRNA and have demonstrated roughly 95% efficacy against symptomatic disease. Johnson & Johnson's filing was supported by data from the pivotal Phase III ENSEMBLE trial showing that Ad26.COV2.S had an overall efficacy rate of 66% at preventing moderate-to-severe COVID-19, four weeks after vaccination.
Its effectiveness also varied by region, with the level of protection against moderate-to-severe disease being 72% in the US at 28 days post-vaccination, dropping to 66% in Latin America and 57% in South Africa, where the highly transmissible B.1.3.5 strain was predominant. However, FDA staff noted in briefing documents released last week that Ad26.COV2.S showed benefit "against severe/critical COVID-19 that was similarly high across the US, South Africa and Brazil," reducing cases of serious illness in those countries by 85.9%, 81.7% and 87.6%, respectively.
At the FDA advisory meeting, which took place Friday, panel members suggested a key challenge for Johnson & Johnson's candidate will be explaining to the general public how it compares to the other vaccines. "We have a vaccine now that has good efficacy that everyone is going to compare to the existing vaccines and say it doesn't look quite as good," remarked panelist Eric Rubin. However, he said "I think it's a relatively easy call. It clearly gets way over the bar and it's nice to have a single-dose vaccine."
In their briefing report, FDA staff reviewers also found "no specific safety concerns" linked to Ad26.COV2.S in the ENSEMBLE trial, although their analysis highlighted some cases of thromboembolic events, including deep vein thrombosis and pulmonary embolism, that were numerically slightly more common among vaccine recipients than for placebo, and that the agency considers these to be "of clinical interest." Meanwhile, FDA medical officer Yosefa Hefter noted there are still unknowns about the vaccine, including the duration of immune protection and the safety and effectiveness in children.
However, several advisory panel members stressed the urgency of fighting the COVID-19 pandemic. "We're in a race between the virus mutating, new variants coming out that can cause further disease and stopping it," commented Jay Portnoy, adding "we need to get this vaccine out. I do believe the evidence supports its safety and effectiveness."
Johnson & Johnson is manufacturing the drug substance for the vaccine at plants in Baltimore, the Netherlands and India, while additional steps in the production process and filling vials with the vaccine are being handled at facilities in Indiana, Michigan and Pennsylvania, as well as Spain and other countries. Each vial of the vaccine contains five doses.
Meanwhile, the company recently submitted a conditional marketing application with the EU, where officials have said deliveries of the vaccine could get under way in early April, while it has also filed for an emergency-use listing with the World Health Organization. In addition, rolling submissions for the candidate have been started in several countries worldwide.
The drugmaker is testing a two-dose version of Ad26.COV2.S, with results expected this summer. Johnson & Johnson has also begun work on a second-generation vaccine that would better target the South African variant, with Phase I trials slated to get under way by this summer as well.
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